Chromium coatings by electrolytic baths are currently used as a decorative layer protecting against corrosion. These coatings are generally made with electrolytic baths.
In these conventional baths, plastics are not conductors, therefore they require being subjected to complex pretreatment process in order to be able to receive the coatings.
New methods for chrome plating by means of physical vapor deposition (PVD) which allow using less toxic products are currently being developed. PVD technology starts directly from the solid material which is to be deposited to then convert it into vapor by means of heating it or bombarding it with energetic ions. The vapor formed condenses on the surface of the substrate, forming a thin layer. The process is performed under vacuum or in a controlled atmosphere to prevent the interaction of the metal vapor with the air. A coating process by means of this method is described in patent application ES 2 239 907 A1.
In order to create a chrome plating, either on plastic or on metal surfaces, copper is first deposited on the surface of the product. This layer is about 20 to 25 microns thick. A deposition of nickel of approximately 15 microns is then carried out and finally the chromium is applied with a typical thickness of about 0.5 microns. In the event that a matte appearance is to be conferred, the last layer of nickel is matted before applying the chromium. However, if the part is to have matte and shiny areas, the area or areas with an appearance different from the majority of the part should be independently inserted, giving rise to an additional complexity. Currently, matte areas can be achieved with the application of organic layers in a partial manner on the chrome-plated shiny surface. This solution has problems of definition in the border of the different finishes and of resistance with respect to the outdoor demands required in automotive applications such as adherence, scratch resistance, etc.